Advances in Fingerprint Technology.pdf

Note: Store in a dark bottle at room temperature.
Working Solution
Solution A 99 parts
Solution B 1 part
Notes: Make just before using: the working solution is stable for only about 15 min.
Develop prints in the absence of fluorescent lights if possible.
Preparation of Colloidal Gold
Stock gold: Prepare a 10% (w/v) solution of tetrachloroauric
acid in high-quality distilled water. This solution is stable
indefinitely at room temperature.
Stock sodium citrate: Prepare a 1% (w/v) solution of sodium
citrate in distilled water. This solution is stable indefinitely at
room temperature.
1. Add 1 mL stock gold solution to 1 L distilled water and bring to a boil.
2. Gently add 10 mL stock sodium citrate solution and boil gently for
10 min. The final solution should be the color of port wine.
3. Stir in 5 mL Tween 20 while solution is still hot and then allow to cool.
4. Adjust the pH to about 3 with 0.5 M citric acid (usually about 1 mL
is required).
5. Restore the solution volume to 1 L. Some volume is lost during the
boiling steps.
6. Store the solution in a scrupulously clean glass or plastic container in
the refrigerator. The solution is stable for several months at 4°C.
Procedure
1. If item to be tested is paper, soak it in several changes of distilled water
for 20 to 30 min. Do not use maleic acid.
2. Place the item to be tested in the colloidal gold solution for 30 to 120 min.
3. Rinse the item with distilled water.
4. Place the item in the silver developer (modified PD working solution)
for 5 to 15 min.
5. Thoroughly rinse the item in distilled water.
6. Air dry the item and photograph the latent prints.
Saunders found that this procedure worked well with many surfaces and
materials, such as computer floppy disks, adhesive tapes, metals, papers,
Styrofoam, credit cards, and glass. It also can be used for specimens that have